E.L. is out of prison and quickly involved in a new scam - stealing a million dollars from the Mob. Unfortunately, he's unaware that the Mob got it from fencing Nazi diamonds. Meanwhile, accountant Lionel Whitney is in town to get married to his dominating fiance, and quickly finds his plans gone awry when Tenspeed hides the diamonds in his limousine. Both groups are now after both him and Tenspeed.
Lionel finds himself being pursued by Nazis and mobsters who are after the diamonds that Tenspeed hid on him. Lionel manages to talk Tenspeed into doing the right thing by appealing to his conscience (such as it is) and running a scam to get everyone arrested. With Tenspeed out on parole and needing a job, Lionel decides to finance a new detective agency with the reward money to fulfill his lifelong dream of being a hard-boiled detective.
Lionel and E.L. form a detective agency and get their first case: an unidentified man who is willing to pay lots of money to find a woman.
Lionel takes a fancy to a client who claims someone is trying to kill her and then leads Lionel and E.L. around in circles while putting killers on their trail.
A stockbroker and friend of Lionel's hires the detectives to investigate two men who are having him make investments with negotiable bonds.
Pressure is put on Lionel and E.L. to create a phony investigation for their client: a woman looking for her missing brother who was working on a super computer.
E.L. gets his old partner, Mike McGill, to run a scam to pay Lionel with con money to keep the agency afloat. However, the fake crime that they set up uncovers a real one, and the crooks will do anything to keep it quiet.
A mobster goes after Lionel and E.L. after they help his girl friend dump him so she can run off with a lounge singer.
E.L.'s nephew's appearance is concurrent with that of thugs who are after a book which E.L. knows nothing about.
Lionel receives a hot birthday present from E.L., while E.L.'s probation officer is trying to find a way to get E.L. put back in prison.
When Lionel investigates the 40-year-old murder of a woman, people start shooting at the partners.
E.L. comes up with a get rich quick scheme when he learns that the Agency's cleaning lady is a descendent of the Russian royal family.
Lionel and E.L. set out to discover if a ""random"" killing by a mental patient was in fact the work of a hired killer.
E.L. helps Lionel impress his visiting parents by arranging for him to gain access to a luxurious office, belonging to diamond thieves, which Lionel can claim as his own.